Push bench



H. WOHLNICK April 9,1935.

PUSH BENCH Filed Aug. 27, 1954 wmzw flaw, 4M5

L J I.

Patented Apr. 9, 1935 PATENT OFFICE PUSH BENCH Hans Wohlnick, Dusseldorf, Germany, assignor to Schloemann Aktiengesellschatt, Dusseldorf, Germany, a corporation of Germany Application August 27;

1934, Serial No. 741,646

In Germany September 1, 1933 1 Claim.

My invention relates to push benches for making tubes and other hollow articles, and more particularly to the means provided in such benches for guiding the mandrel and its carrier.

It has already been proposed to employ guiding means for that purpose which are moved sideways by the advancing rack bar which drives the mandrel and its carrier to make room. Means of that kind are subject to rapid wear or even breakage by the heavy shocks and impacts from the rack bar. A further drawback is that these guides engage the mandrel and its carrier at intervals only and not along their entire length.

To obviate these drawbacks, stationary guide all over the length of the mandrel and its carrier and have the form of a tube or a hollow prism. With this type of guide means, the mandrel shaft which is enclosed by them cannot directly be engaged by the rack bar so that an intermediary member was necessary to couple the rackbar with the mandrel carrier which member extended through a slot in the stationary guide. The rackbar and the mandrel carrier could therefore not be arranged in the same axis and the force exerted on the mandrel carrier by the advancing rackbar was eccentrically transmitted to the former, thus subjecting the latter to a momentum which was considerable in view of the heavy forces required for pushing the mandrel and the work piece through the dies. For this reason, the rackbar and its bedplate had to be made very large to take'up this momentum whereby they became very expensive.

It is further old to arrange two rack bars side by side and transmit their movement by a sort of crosspiece connecting them. In this construction also the rack bars were not symmetrically arranged with respect to the axis of the mandrel and its carrier and therefore the force was eccentrically transmitted to them. Furthermore, this arrangement called for a very wide bed plate to accommodate the two opposite rack bars which is a further drawback. 1

In another construction, there'is one rack bar with teeth on opposite sides and meshing with two pinions. In this instance, the mandrel carrier can be symmetrically arranged with respect to the rack bar, but it is not possible there, to provide stationary guides so that movable guides means have already been proposed which extend had to be used which had, of course, the above mentioned disadvantages.

My invention has for its object to provide a push bench in which the guides of the mandrel carrier are stationary and in which at the same 5 time these parts are so arranged with respect to the rack bar that the force is transmitted to the mandrel carrier without causing a detrimental momentum. I

According to this invention, I make the rack 10 bar of H shaped cross section, the flanges of the H being externally provided with teeth and stationary guides being arranged symmetrically to the rack bar and in the spaces between these flanges at both sides of the web of the H.

In the annexed drawing, on which I have illustrated an embodiment of my invention,

Fig. 1 is a cross section of the bench,

Fig. 2 a side elevation, and

Fig. 3 a plan view of the rack-bar and the drive 20 ing pinions.

According to my invention, the rack bar I of the novel push bench is H shaped, and is supported by a bed plate 2. 3 and 4 are guides for the. mandrel carrier 5, arranged in the spaces be- 25 tween the flanges of the H and at both sides of its web. The guides are stationary in the sense, that they arenot moved by the advancing rack bar, but are so constructed as to be readily removable when desired. The flanges of the rack 30 bar are toothed on their outer sides and in mesh with pinions 6 (Fig. 3).

As the teeth are arranged symmetrically with respect to the axis of the mandrel and its carrier,

the force will be transmitted to the former with- 35 out any momentum.

The mandrel and the dies are not represented here as they form no part of my invention and can be of any desired type.

I claim as my invention:

In a push bench for making tubes and other hollow articles, a mandrel carrier, a rack bar for advancing said carrier, said rack bar being symmetrically arranged with respect to said carrier and having the shape of an H, teeth on the outer 45 v sides of the flanges of saidrack bar and stationary guide members for said carrier in the spaces between the flanges at both sides of the web of the rack bar.

. HANS WOHLNICK. 

